Oral cancer accounts for over 30,000 cases of cancer per year in the United States and is the sixth most common cancer worldwide. The five-year survival rate (approximately 50%) from these carcinomas is one of the worst for the major sites of cancer development, and has not significantly improved in the past 30 years. Reliable molecular markers that can predict this transition early in the process and be screened for in readily obtained clinical samples would enable more informed treatment and monitoring of patients, and help to significantly improve the prognosis of oral cancer patients. The overall objective of the proposed work is to address this critical need by identifying protein biomarkers in whole human saliva that are predictive of oral cancer development. This objective will be achieved through three Specific Aims: 1) Characterize changes in the secreted saliva proteome associated with oral cancer progression;2) Characterize changes in the exfoliated oral epithelial cellular proteome and tissue biopsies associated with oral cancer progression;3) Validate candidate predictive oral cancer protein biomarkers via targeted mass spectrometric analysis. Strategies developed by the assembled research team, including novel peptide fractionation methods, targeted mass spectrometry-based biomarker validation methods, and enabling computational and bioinformatic tools will be employed. A highly informative oral cancer progression model will be analyzed, composed of unique clinical samples collected from individuals at intermediate stages of oral cancer development, controlling for the risk factor of smoking, and enabling the identification of diagnostic protein changes at the earliest stages of cancer development. Taken together, the combination of advanced technologies, availability of unique clinical samples, and the collective expertise of the assembled research team will provide for the successful discovery and validation of promising clinical biomarkers of oral cancer. RELEVANCE TO PUBLIC HEALTH: The proposed studies will identify proteins in clinical saliva samples that are predictive of oral cancer development, providing promising diagnostic markers which can be developed into routine clinical patient tests. As such the findings from the proposed studies will have a direct impact on improving the diagnosis and treatment of oral cancer in the clinic, thereby leading to a decrease in the significant suffering and death caused by this cancer.